In general, when ground members and devices, such as a sign, a guardrail and a solar panel, are fixed to the ground such as soil or concrete, anchor piles are embedded to enhance a resistance force in the ground, and thus a support force is strengthened
In particular, in mega-solar power plants which have seen extensive growth in construction due to the promotion of the utilization of renewable energy in Japan in recent years, a large number of solar panels may be installed on a vast tract of land which is significantly affected by the natural environment (which is particularly affected by wind). There are also concerns that the solar panel installed under such environment is affected by, for example, wind blown up from the ground surface so as to be floated up as a whole, and that when a resistance force of the anchor pile in the ground is weak, the solar panel may be blown away in the worst case, which leads to a major accident. Hence, high expectations are placed on technology development for enhancing the resistance force of the anchor pile in the ground.
Conventionally, for an anchor pile embedded in the ground, a steel pipe has been generally used, and in order to enhance a resistance force in the ground, for example, the diameter of the pipe has been increased.
For example, Patent Literature 1 discloses an anchor pile in which a predetermined resistance member is formed around a pipe to enhance a resistance force in the ground.
Specifically, as shown in FIG. 11, on the side surface of a pipe 102, a spiral member 103 is formed in a spiral shape. In order for an anchor pile 101 described above to be embedded in the ground, the anchor pile 101 is driven while the entire anchor pile 101 is being rotated, and thus the anchor pile 101 enters the ground while a cutting teeth 104 at a tip end is breaking up soil. Here, the spiral member 103 serves as a guide when the pipe 102 is rotated and pressurized to be embedded in the ground. Furthermore, after the anchor pile 101 is driven into the ground, the spiral member 103 serves to provide a resistance force in the ground so that the anchor pile 101 can be held in a stable state see (Patent Literature 1).